Just got my FFE last month. So far so good. But just noticed last week that when the battery showed fully charged, after I drove about 60 miles, on the trip 1 information panel (enhanced view mode), it said about 15 kw has been used. But the battery gauge indicated only 5 miles left. It showed 210w/mile on the panel. I was a bit confused since the battery capacity is 23kw and I charged it fully. The drive range looks right, but electricity usage seems not quite make sense, or is that what FFE supposed to do? Anyone has same problems?
23kw battery issue
- Thread starter silverjie
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hybridbear
Well-known member
23 kWh is the total capacity, not the usable capacity. If the battery was charged from 0 kWh up to 23 kWh and back down to 0 again it wouldn't last very long. There is a buffer built in to protect the battery.silverjie said:
WattsUp
Well-known member
The usable battery capacity for the FFE is about 19 kWh, or about 80-90% of the total capacity. The car maintains a buffer of about 10% "at each end" of the battery to avoid under- and over-charging, both of which are damaging to lithium-ion batteries. This is not specific to the FFE. All EVs employ a similar strategy.hybridbear said:
Thanks WattsUp and hybridbear. I learn from this forum that GOM is not very accurate to give best estimation on how many miles left. But seems looking at battery usage is also not reliable since you are not sure the usable battery capacity of you FFE. So maybe 19kw is close to the limit.
WattsUp said:
WattsUp
Well-known member
We're pretty sure it is somewhere between 18.5 and 19.5 kWh, based on all reported use cases. Granted, that is not exact.silverjie said:
Also, even though the FFE battery is temperature managed, the usable capacity does still vary with the ambient temperature. It very cold weather, the battery performance can be noticeably curtailed (and this is simply due to the effects of cold on the battery itself, not even considering the likely increase in the cabin heater usage, which will also lead to reduced range due to increased energy consumption). In very moderate climates, the battery will probably seem to have about the same range year-round.
Mine is at 17.5 usable as reported by my car. For computation sake, I take the amount of KWhs consumed shown on the trip display and divide it by (100%-value shown on the "Leaf" display. For instance if 70% of my battery is remaining and I look at how much energy has been consumed since I charged up to 100% and is is 5.16KW, I take 5.16 / (100%-70%) = 17.2KW.
I'm not sure, but I suspect, that the method for which the power consumption is calculated is not 100%, but it is hard to be certain. I typically drive 50% of my commute on freeways going, on average, 75MPH. The other 50% is on surface streets tavelling at 55MPH (This is the posted speed limit). My average Watthours per mile is 275, which seems low considering how I drive the car. If the car reads lower than actual, then the capacity would read lower than actual. Also, I haven't seen any degradation in battery capacity since I got the car, and, when I had the battery replaced, there was no change in capacity.
But even if it were lower for some reason, it wouldn't really matter. I have plenty of range for how I use my FFE.
I'm not sure, but I suspect, that the method for which the power consumption is calculated is not 100%, but it is hard to be certain. I typically drive 50% of my commute on freeways going, on average, 75MPH. The other 50% is on surface streets tavelling at 55MPH (This is the posted speed limit). My average Watthours per mile is 275, which seems low considering how I drive the car. If the car reads lower than actual, then the capacity would read lower than actual. Also, I haven't seen any degradation in battery capacity since I got the car, and, when I had the battery replaced, there was no change in capacity.
But even if it were lower for some reason, it wouldn't really matter. I have plenty of range for how I use my FFE.
michael
Well-known member
There seems to be (certainly is in my car) a good deal of nonlinearity in the first 10% or so of discharge. The percentage falls very fast in the first few miles.
I think you can get a better estimate of the end point by taking a half dozen readings of percentage and kWh consumed and plot it. Do a straight line best fit between 90% and the lowest readings you can reach, extrapolate to zero %
Or put into excel and do a linear regression.
Doing your calculations starting at 100% will underestimate the end point. Or drive it to zero. Then you'll know for sure...
I think you can get a better estimate of the end point by taking a half dozen readings of percentage and kWh consumed and plot it. Do a straight line best fit between 90% and the lowest readings you can reach, extrapolate to zero %
Or put into excel and do a linear regression.
Doing your calculations starting at 100% will underestimate the end point. Or drive it to zero. Then you'll know for sure...
I've run my battery to zero...which is another interesting story, and, it is 17.5. The previous was just an example, but you are right, at 70% it is very non-linear. The only reason I think the error is with the measurement of the energy consumption is that my range seems to be in-line with what others see...chime in if you get something different...
-I drove at about 65mph on a trip from Orange County to San Diego (69mi) and had 13mi to spare.
-On the way home, I started at 65mph, but ended up at 55mph for the last 25miles and had only 3mi to spare when I got home....likely due to altitude changes?
As for my battery story, I did a dumb thing in over-estimating my remaining battery range on a basically uphill trip. I made it to my destination, but I only had 2mi remaining on a 7 mi trip; however, most of the trip was downhill...except for an initial uphill ascent within the first 2 miles. I made it about 200 yards from the crest of the hill when the car gave me the battery depleted message. I called roadside assistance and was given an hour window. After sitting for about 15minutes, I decided to see if the car would let me go again. Sure enough, I hit start and although I got the depleted message again, the car did go and I got over the top of the hill. I was able to coast downhill and get some regen energy to get me over a flat spot but rather than tempt fate, I turned into a Walgreens that happen to have a charging station. I may have been able to make it home, but to try would have been more stupidity.
Anyway, the point I'm trying to make with this is if you find yourself a few hundred feet from safety / home / or a charging station. Wait a bit and re-start the car. You might get the little push you need to made a difference.
-I drove at about 65mph on a trip from Orange County to San Diego (69mi) and had 13mi to spare.
-On the way home, I started at 65mph, but ended up at 55mph for the last 25miles and had only 3mi to spare when I got home....likely due to altitude changes?
As for my battery story, I did a dumb thing in over-estimating my remaining battery range on a basically uphill trip. I made it to my destination, but I only had 2mi remaining on a 7 mi trip; however, most of the trip was downhill...except for an initial uphill ascent within the first 2 miles. I made it about 200 yards from the crest of the hill when the car gave me the battery depleted message. I called roadside assistance and was given an hour window. After sitting for about 15minutes, I decided to see if the car would let me go again. Sure enough, I hit start and although I got the depleted message again, the car did go and I got over the top of the hill. I was able to coast downhill and get some regen energy to get me over a flat spot but rather than tempt fate, I turned into a Walgreens that happen to have a charging station. I may have been able to make it home, but to try would have been more stupidity.
Anyway, the point I'm trying to make with this is if you find yourself a few hundred feet from safety / home / or a charging station. Wait a bit and re-start the car. You might get the little push you need to made a difference.
WattsUp
Well-known member
I see you're in SoCal, but did it happen to be very cold when you got 17.5 kWh? Sounds kinda low.davideos said:
I've done the same (0 miles, 0% SOC) and was at 18.4 kWh.
WattsUp
Well-known member
I guess I should qualify that with "under ideal conditions" (e.g., not too hot, not too cold).WattsUp said:
I've checked all year round. I do notice a drop when it gets cold, but spring / fall / summer, all pretty much the same. I've even tried driving super conservatively...and although I can go further, the consumption and battery level % seem to correlate.
WattsUp
Well-known member
...also you need to consider your rate of consumption (average Wh/mi) which is also variable. But, this is basically what the GOM is doing for you. More or less the estimated range shown by the GOM is simply your remaining battery kWh charge divided by the current Wh/mi.silverjie said:
(It's technically not THAT simple... the car seems to keep some sort of rolling average, or averages, and also adjusts for climate usage, etc.... but the GOM number is basically the result of simple math that is constantly being applied while you drive.)
fbitz777
Well-known member
I typically get 19.5Kwh but last few weeks at 20F outdoor I have been getting more like 19Kwh. When I get started and during the first half of the battery in cold weather it seems that it would be more like 18kwh but things seem to improve in the second 50%.WattsUp said:
No cabin heat for me ...can't afford to go down to 50mile of range.
